Illuminated counter



June 26, 1962 c, MATHEWS 3,040,458

ILLUMINATED COUNTER Filed Oct. 14, 1960 g C IINVENTOR.

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BY C5 2 ATTOk/E United States atent C 3,040,458 ILLUMINATED COUNTEREdward C. Mathews, Flushing, N.Y., assignor to Simmonds PrecisionProducts, Inc., Tarrytown, N.Y., a corporation of New York Filed Oct.14, 1960, Ser. No. 62,777 Claims. (CI. 40-77) The invention relates toimprovements in integral lighting and, more particularly, to thelighting of counter wheels by encompassing them with a transparentsleeve, the inner surface of which has indicia suitably applied theretoby my method set out in United States patent application Serial No.154,310, filed November 22, 1961.

The theory of light piping through highly refractive media by virtue oftotal internal reflection of light rays, making greater than a criticalangle of incidence with the walls of the medium, is well-known in theart. However, up to the present time this method has had the inherentdisadvantage that it is impossible for such light to enter the mediumthrough one of the surfaces by Which light is internally reflected.Heretofore, such devices have always had the light introduced through anedge of some auxiliary surface other than those which confine the light.

Accordingly, the principal object of the invention is to provide acounter wheel or other indicia bearing medium in which light enters theouter walls of the transparent sleeve in such a way that it makes almostcritical angles of incidence with the wall of the sleeve on internalreflection.

Another object of the invention is the elimination of bright spots whichnormally occur in the presently used devices due to the placement of thelight source.

A still further object of the invention is to provide an arrangementreadily adaptable to a standard type counter with very lit-tiemodification.

Still another object of the invention is to provide a lighted indiciabearing medium of simplified construction which will give superiorresults.

A still further object of the invention is to provide a lighted counterwhich gives substantially uniform illumination as well as high contrastbetween the numerals and the supporting background.

Another advantage of this invention is to provide a lighted counterwhich gives even uniform illumination,

less glare and high contrast between the numerals or other indicia andthe background.

In the accompanying drawing illustrating the invention, in the severalfigures of which like parts are similarly designated:

FIGURE 1 is a cross sectional view of the counter wheel illustrating theinvention.

FIGURE 2 is a perspective view of the invention.

Referring now to the drawing for a more detailed description of theinvention and more particularly to FIG- URE 1 there is shown a counterwheel upon which is in serted a transparent ring 2. This ring can bemade of any transparent material such as plastic, glass, or some similarmaterial. The counter wheel 4 is usually of opaque material such asmetal, nylon, etc. and is of standard manufacture and can be readilyobtained from a number of sources.

It is not practical to introduce the light through the edge of a counterwheel enveloped by a light piping medium. In this applicants concept,the illumination depends on light which enters the outer walls of theglass cylinders in such a way that it makes almost critical angles ofincidence with the walls of the cylinder on internal reflection. Thepath of a typical light beam is shown in FIG. 1. The light rays enteringthe counter by making small angles with the tangent of the counter re-Patented June 26, 1962 sults in that portion of the light which entersby refraction having nearly critical angles of incidence on subsequentreflections. The optimum path by which light travels from the lightsource to the indicia depends upon two phenomena. One, the efficiencywith which the light initially enters by refraction and two, theefliciency with which the light is reflected on subsequent multiplereflections. The first phenomenon has its greatest efliciency when thelight approaches the refractive medium perpendicularly. This, however,results in angles of incidence within the refraction medium which givevery low efficiencies of internal reflection. Conversely when the rayapproaching this refraction medium does so making a very small anglewith the tangent, the efiiciency of initial transmission is poor, butsubsequent internal reflections occur at nearly their critical anglesand therefore have high efliciency. A compromise between these twoextreme conditions is therefore required. Since, however, the initialtransmission of light occurs only once and the subsequent internalreflections occur very many times in normal configurations, thecompromise must favor the condition in which a large loss is accepted atthe initial transmission thereby giving high efliciencies in the oftenrecurring internal reflections. For this reason, this invention requireslight approaching at an angle close to the tangent to the surface of thecounter.

It is to be understood that the remaining rays are not being blocked outas these rays do not detract from the operation of the invention.However, the excellent illumination that is realized is due to the rayswhich enter as described above.

The viewing mask, indicated at 1, is positioned in close proximity withthe counter wheel 4, but not in intimate contact therewith. Illuminationof the indicia 3 carried by wheel 4 is indirectly supplied by lightedbulb 5. It is to be noted that light source 5 can be in any position aslong as it is behind mask 1 and in line with counter wheel 4. Thenumerals or indicia 3 are applied on the inside of the transparent ring2 by any suitable process. The light rays entering the transparent ring2 at an angle from light source 5 are retained in the transparent ring2, as shown in FIGURE 1, and are reflected outward from the numerals orindicia 3 at the display window provided in the mask 1. Therefore, itcan be seen that only the numerals or indicia 3 are illuminated as theyrevolve past the opening in the mask 1. There can be no wetting of theinterface between transparent ring 2 and counter wheel 4. Any substancethat wets the interface causes light to be absorbed from the wetted arearesulting in reduced illumination of the numerals or indicia 3.

Referring now to FIGURE 2 there is shown a three dimensional view of thetransparent ring 2, on which inner surface numerals or indicia 3 havebeen placed. A certain relative size is illustrated for the transparentring 2. It is to be understood that transparent ring 2 can vary inthickness, width and diameter according to the size of the counter wheel4 which is shown in FIGURE 1.

It is to be understood that the present invention is not to be limitedto counter wheels but is applicable to any curved surface or wheel suchas a flexible transparent tape.

Although a single embodiment of the present invention has beenillustrated and described in detail, it is to be expressly understoodthat the invention is not limited thereto. Various changes can be madein the design and arrangement of the parts without departing from thespirit and scope of the invention as the same will now be understood bythose skilled in the art.

What is claimed is:

1. A device of the type described comprising a drum provided with anopaque periphery, a transparent ring encompassing said periphery,indicia applied to the inner surface of said ring, a light source spacedfrom the periphery of said transparent ring for supplying light rays toprovide illumination of said transparent ring, said light rays makingsmall angles with the tangent of said ring whereupon that portion of thelight which enters by refraction has nearly critical angles of incidenceon subsequent reflection.

2. A device of the type described in claim 1, wherein an opaque surfaceprovided with a viewing aperture is positioned in close proximity to thetransparent sleeve, said viewing aperture being arranged to permitseriatim observation of said indicia.

3. An illuminated counter comprising an opaque drum around which drum atransparent sleeve is encompassed, indicia applied to the inner surfaceof said transparent sleeve and a light source positioned along theperiphery of said transparent sleeve for supplying light rays to provideillumination of said transparent sleeve, said light rays making smallangles with the tangent of the sleeve whereupon that portion of thelight which enters by refraction has nearly critical angles of incidenceon subsequent reflection.

4. A device of the type described comprising a drum provided with anopaque perimeter, a transparent sleeve supported by said drum, indiciaapplied to the inner surface of said transparent sleeve and a lightsource disposed exteriorly of said sleeve and serving to direct a beamof light upon the perimeter of said sleeve to illumine the indiciacarried thereby.

5. In indicator means, a support member, transparent sleeve meanscarried exteriorly of said support member, said sleeve means beingprovided at its surface adjacent to said support member with legibleindicia and means to direct a beam of light upon said sleeve means froma source exterior thereto.

References Cited in the file of this patent UNITED STATES PATENTS1,648,977 Weidner Nov. 15, 1927 1,696,489 Kahn Dec. 25, 1928 2,159,095Madan May 23, 1939 2,259,910 Rylsky Oct. 21, 1941 2,499,824 Haecker Mar.7, 1950 2,640,144 Levy May 26, 1953 2,737,744 Sturges Mar. 13, 19562,795,878 Welland June 18, 1957

